This invention relates to medical apparatus for the induction of reflexive responses in a patient. It has particular but not exclusive application to inducing a coughing reflex in human patients, and for illustrative purposes, reference will be made to such application. However, it is to be understood that the apparatus may be used in other applications, such as inducing other reflexive responses and/or similar responses in animals.
It is well known that the coughing reflex is a vital part of maintaining normal lung function, as it acts to rid the lungs of excessive secretions such as mucus or inhaled substances. In some cases, human patients and animals are unable to cough on demand, rendering them liable to the exacerbation or prolongation of respiratory problems.
Those people who are unable to cough on demand include the very young, gravely ill and incapacitated patients, unconscious or heavily sedated patients, patients who have undergone a near-drowning experience or overdosed on drugs which have suppressed their central nervous system, victims of stroke, elderly patients who have lost control of their bodily functions, intubated and incubated patients with temporary airways such as those in intensive care situations and patients who are anaesthetised during or immediately post surgery. Such conditions also exist in the veterinary context for animals.
Prior art methods of clearing the upper respiratory tract of mucous or to induce a coughing reflex is usually through the introduction by intubation of the upper airway tract such as vacuum drainage or pulmonary lavage catheters. The problem with the introduction of such devices is that this is an artificial and largely inefficient method to clear mucus or other secretions blocking the lower respiratory airways. To be precise, it does not have the benefit of the explosive clearing mechanism normally associated with a coughing spasm. Furthermore, while the upper respiratory tract may be cleared by suction, smaller airways, such as the bronchi and bronchioles cannot be so easily cleared.
Every year, tens of thousands of people die because of respiratory problems. Foremost among these deaths are sufferers of the following conditions:
respiratory illness;
bronchitis (acute and chronic);
pneumonia;
chest infections (bacterial and microbial);
pediatric respiratory problems;
cystic fibrosis;
bronchiolitis (a pediatric form of bronchitis);
bums injuries;
drowning, and
self-aspiration, for example after a drug or alcohol overdose.
Many of these people die because their lungs fill with excessive secretions or fluids. The usual method of self-clearing the lungs is to cough. However, huge sections of the population are unable to cough effectively, rendering them vulnerable to respiratory problems and premature death.
Even in a hospital environment, the method of clearing the chest of such patients are ineffective. Usually, a suction catheter is used to draw the secretions out of the lungs. One major problem with this method is that only the very uppermost airways are cleared. As the catheter cannot penetrate to the mid or lower airways, almost all of the secretions stay put. Pneumonia and chest infections are frequent sequelae.
Furthermore, a suction catheter is not readily transportable outside a hospital—for example, to a beach, a park or a nursing home. The only truly effective way to clear the lower airways of the lungs is of course to cough.
Medical staff have tried many techniques over the years to stimulate the all-important coughing reflex Methods have included manual pressure to the front of the neck, blowing dry oxygen down the throat, and tickling the back of the palate with a catheter. None of these methods has proved reliably effective. The catheter-tickling method can sometimes even be dangerous as the patient can gag and then aspirate the vomitus. In short, no simple method currently exists to stimulate an all-important coughing reflex
The coughing reflex is therefore a natural mechanism wherein air is expelled under force which clears the pulmonary system from the smallest airway towards the trachea. The situation is even more acute with heavily sedated or unconscious patients or animals wherein the smaller airways are blocked and cannot be cleared by the introduction of suction tubes. Respiration can be compromised to the extent where the respiratory centre is completely depressed through hypoxia and the patient or animal eventually dies from asphyxiation, infection or pneumonia.